window.addEvent('domready', function() {
	var el = $('myElement');
	var visibile ='no';
	
	$('tweenOpacity').addEvent('click', function(e) {
										
											if (visibile == 'no') {

			var div = $('myElement').setStyles({display:'block',opacity: 0 }); 

		e.stop();
		el.fade(1);
		visibile = 'yes';
											} else {
											 

		e.stop();
		el.fade(0);
		
		var myNascondi = function(){ $('myElement').setStyles({display:'none',opacity: 0 }); };
//attendi
myNascondi.delay(550); //nasconde
		visibile = 'no';
							}
											
											});
									 
						});